1. Field of the Invention
The present invention relates to an imaging apparatus applied to a medical diagnostic imaging apparatus, a non-destructive inspection apparatus and an analysis device using radiation; and a radiation imaging system. In the present specification, the radiation shall include X-rays, alpha-rays, beta-rays and gamma-rays.
2. Description of the Related Art
In recent years, a panel using a thin film transistor (hereafter referred to as “TFT”) as a switch element can be mass-produced, because a technology for manufacturing a liquid crystal panel using the TFT has been developed, and an area sensor having a photoelectric conversion element has been used in each field (for instance, X-ray imaging apparatus). A radiation imaging apparatus has characteristics of converting a faint signal digitally and outputting an image, which are different from those of the liquid crystal panel. For this reason, when a substrate is electrically charged in a manufacturing process and a potential difference is formed, for instance, between a signal line and a gate line, a threshold voltage (Vth) of a TFT for reading is shifted and the TFT can not read the faint signal. When the above described potential difference is large, the device is broken, which leads to severe lowering of a yield in a mass production line.
For this reason, U.S. Pat. No. 6,586,769 discloses a method of connecting gate lines (hereafter referred to as “gate wiring”) for controlling TFTs to each other, common electrode bias lines (hereafter referred to as “bias wiring”) to each other, which control photoelectric conversion elements, and the gate wiring to the bias wiring, all with a semiconductor layer having high resistance. In addition, in a TFT matrix panel before a glass plate is cut, signal wirings are also connected to each other through high resistance.
In the method, when the TFT matrix panel is actually used, the glass plate is cut, and at the same time, signal wirings which have been connected with each other through high resistance are electrically separated. As a result of this, the wiring on the TFT matrix panel after the glass has been cut is electrically independent till a signal processing IC or a source driver is connected. Accordingly, when the panel has received an electrostatic influence from the outside, the panel cannot dissipate static electricity to neighboring wirings, and consequently can not cope with the static electricity.
As a result of this, particularly the signal wiring of the panel is electrostatically loaded, and consequently some or all of TFTs connected to particular signal wiring inevitably causes the shift of Vth. Then, such an apparatus as to manipulate a faint signal recognizes the shift of Vth as the variation of the signal due to a fluctuation of the Vth in the TFT connected to particular signal wiring, or as a sense of incongruity in a captured image. In some cases, the apparatus cannot transfer the signal and causes a line defect.
In addition, U.S. Patent Application Publication No. US-2003-0030054 discloses a method of coping with static electricity.